Early menstrual cycle impacts of oestrogen and progesterone on the timing of the fertile window
Bibliographic record
Abstract
STUDY QUESTION: What is the effect of oestrogen and progesterone at the beginning of the menstrual cycle in delaying entry into the fertile window? SUMMARY ANSWER: Both oestrogen and progesterone contribute to a delay in the onset of the fertile window. WHAT IS KNOWN ALREADY: Oestrogen enhances cervical mucus secretion while progesterone inhibits it. STUDY DESIGN, SIZE, DURATION: Observational study. Daily observation of 220 menstrual cycles contributed by 88 women with no known menstrual cycle disorder. PARTICIPANTS/MATERIALS, SETTING, METHODS: Women recorded cervical mucus daily and collected first-morning urine samples for analysis of oestrone-3-glucuronide, pregnanediol-3-alpha-glucuronide (PDG), FHS, and LH. They underwent serial ovarian ultrasound examinations. The main outcome measure was the timing within the cycle of the onset of the fertile window, as identified by the appearance of mucus felt or seen at the vulva. MAIN RESULTS AND THE ROLE OF CHANCE: Low oestrogen secretion and persistent progesterone secretion during the first week of the menstrual cycle both negatively affect mucus secretion. Doubling oestrogen approximately doubled the odds of entering the fertile window (OR: 1.82 95% CI=1.23; 2.69). Increasing PDG from below 1.5 to 4 µg/mg creatinine was associated with a 2-fold decrease in the odds of entering the fertile window (OR: 0.51 95% CI=0.31; 0.82). Prolonged progesterone secretion during the first week of the menstrual cycle was also statistically significantly associated with higher LH secretion. Finally, the later onset of the fertile window was associated with statistically significant persistently elevated LH secretion during the luteal phase of the previous menstrual cycle. LIMITATIONS, REASONS FOR CAUTION: This post hoc study was conducted to assess the potential impact of residual progesterone secretion at the beginning of the menstrual cycle. It was conducted on an existing data set because of the scarcity of data available to answer the question. Analysis with other datasets with similar hormone results would be useful to confirm these findings. WIDER IMPLICATIONS OF THE FINDINGS: This study provides evidence for residual progesterone secretion in the early latency phase of some menstrual cycles, which may delay the onset of the fertile window. This progesterone secretion may be supported by subtly increased LH secretion during the few days before and after the onset of menses, which may relate to follicular waves in the luteal phase. Persistent progesterone secretion should be considered in predicting the onset of the fertile window and in assessing ovulatory dysfunction. STUDY FUNDING/COMPETING INTEREST(S): The authors declare no conflicts of interest. No funding was provided for this secondary data analysis. TRIAL REGISTRATION NUMBER: N/A.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.010 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".